SAN FRANCISCO (KRON) — A flurry of alerts buzzed phones in the San Francisco Bay Area as the United States Geological Survey reported a 4.1-magnitude earthquake shook 12 miles northeast of Antioch Wednesday morning.

Residents of the Bay Area and beyond with the MyShake app installed on their phones were alerted at 9:29 a.m. when the shaking began. The epicenter of the quake was located in Isleton in Sacramento County.

The MyShake app was developed by the University of California, Berkeley seismological lab and can deliver early warnings of imminent earthquakes. The alerts come from the ShakeAlert Earthquake Early Warning System, which is operated by USGS.

Many commenters on KRON4’s Facebook post mentioned receiving the quake alert on their phones, whether shaking was felt in their location or not.

BART said trains were held after the quake for track inspections, which concluded at 10:30 a.m. Normal service has since resumed with residual delays. The San Francisco Municipal Transportation Agency also said it would conduct track inspections.

There have been no reports of damage from the quake in San Francisco, according to the SF Department of Emergency Management. “It’s a great reminder to do what we can now, before the next damaging earthquake,” the agency said on X.

Yesterday was the 34-year anniversary of 1989’s Loma Prieta earthquake, which killed more than 60 people and injured thousands of others. That infamous quake caused around $6 billion worth of damage.

Tomorrow, Oct. 19, is International ShakeOut Day, and the MyShake app will conduct a test drill by sending an alert to devices at 10:19 a.m. “When you get the alert, practice: DROP, COVER , and HOLD ON!” the app advises.